This invention relates to a frangible connector for joining through assembly and thereafter frangibly connecting the two valve body housings of a self-closing breakaway valve assembly or similar structure.
My U.S. Pat. No. 3,921,656 discloses self-closing breakaway valve assemblies of the type comprising two valve housings joined by a frangible connecting means, each valve housing having mounted therein a rotatable valve member which is spring biased to close. Trigger means in the form of spider members spanning the bores of the rotatable valve members and a trigger ball engaged between the spider members maintains the rotatable valve members open until separation of the housings. Upon separation of the housings, the trigger ball providing engagement between the spider memebers is released, and the rotatable valve members rotate to their closed positions.
In such a self-closing breakaway valve assembly, it is preferable that the spider members be aligned when the rotatable valve members are opened. This provides a smoother flow through the bore of the valve assembly, minimizing turbulence and pressure drops. This can be accomplished in the structure shown in the '656 patent, because the frangible connection is made through radially protruding flanges of the two valve housings, i.e. the valve housings are positioned with the spider members aligned and the frangible rivets, screws or the like are mounted through the radially protruding flanges. However, in many instances it is desirable to enclose the frangible elements within the valve housings to keep the outside diameter of the housings to a minimum and to avoid interference with radial flanges used to mount the housings to bulkheads in aircraft or the like.
In my application Ser. No. 900,329, filed Apr. 26, 1978, now U.S. Pat. No. 4,232,697, there is disclosed a frangible connector for connecting the two housings of self-closing breakaway valve assemblies or similar structures. The frangible connector incorporates a tension ring concentric with and closely receiving a moment arm ring, with tension mode frangible means such as shearable set screws or pins extending across the axially disposed tension ring-moment arm ring interface to frangibly secure the tension ring and moment arm ring together. A bending ring is positioned adjacent the moment arm ring, and the bending ring and moment arm ring are connected by bending mode frangible means such as screws or rivets. The tension ring is adapted for connection to one of the valve housings, such as by being provided with screw threads, and the bending ring is adapted for connection to the other of the housing members, also by screw threads. If the frangible connector is pre-assembled as a unit, alignment of the spider members must be achieved by careful positioning and close tolerances of the threads, so that the spider members end up aligned when the entire assembly is screwed together. Alternately, the frangible mode set screws can be received in slots permitting limited rotation of the two housings to align the spider members, whereafter the set screws are tightened down to secure the housings in the desired position. However, not all self-closing breakaway valve assemblies require the type of frangible connector described in patent application Ser. No. 900,329, and in particular the separate tension mode frangibility is not required in some applications.
Further, it is necessary for the trigger ball to release from both spider members for both rotatable valve members to close. If the ball fails to release from one of the spider members for any reason, the rotatable valve member would not close. Although this is a highly unlikely occurrence, the result of such a failure dictates that every precaution be taken against it, and any improvement in this area is desirable.
Accordingly, there is need for alternate frangible connectors for structures such as self-closing breakaway valve assemblies, and in particular, there is a need for a self-closing breakaway valve assembly incorporating a frangible connector which provides for alignment of spider members in the assembled unit as well as other improvements.